Wind and Waves, Part II

Where do those waves come from, then, that aren't caused by the current wind conditions?  Those waves are called swells, and are generally the remnants of far-off storms, with periods exceeding 10 seconds.  Apparently, waves with short periods tend to dissipate within a couple thousand miles, but waves with longer periods can propagate halfway around the Earth, or even farther, as long as they don't run into a continent.  This is where the really good surfing waves come from, and helps to explain why the West Coast and Hawaii have better surfing than the East Coast.  This is why I bothered listing wave period on my earlier tables (don't worry, I haven't forgotten to post the rest of them).  And that's about where the college intro level of research ends.

To find out how fast waves dissipate and how far they propagate required digging in pretty deep.  This is the "professional" level of research (so my way of thinking goes).  It's also pretty much the "in over my head" level of research.  To get any kind of idea how to work up some game-able numbers, I had to spend several hours finding the exact combination of Google search terms that eventually led to the 1966 edition of thePhilosophical Transactions of the Royal Society of London, specifically the paper Propagation of Ocean Swell across the Pacific, by F. E. Snodgrass, G. W. Groves, K. F. Hasselmann, G. R. Miller, W. H. Munk, and W. H. Powers.  I then spent several more hours poring over 65 pages or so of measurements and equations that were absolutely too complex to use in game preparation, except for the most obsessed, masochistic gamemasters.  Eventually, I happened upon a statement that short period waves decay by about a decibel for every degree of great circle they travel, and later found a series of measurements that gave me some long period decay rates.  Interpolating to find approximate decay rates for wave periods that weren't specifically listed, and reading up on how decibels apply to ocean waves as opposed to noise levels, I've been able to come up with a short table that now shows a game-able approximation of the end of the life cycle of waves.

 

Period	Wave height as a proportion of original height
	90.00%	80.00%	70.00%	60.00%	50.00%	40.00%	30.00%	20.00%	10.00%	1.00%
<10	55	116	186	266	361	478	627	839	1200	2400
10	73	155	248	355	481	637	837	1118	1600	3200
11	110	233	372	532	722	955	1255	1678	2400	4800
12	137	291	465	666	903	1194	1569	2097	3000	6000
13	183	388	620	887	1204	1592	2092	2796	4000	8000
14	275	581	929	1331	1806	2388	3137	4194	6000	12000
15	366	775	1239	1775	2408	3184	4183	5592	8000	16000
16	549	1163	1859	2662	3612	4775	6275	8388	12000	24000

So, a wave with a height of 28 feet and a period of 8 seconds will have a height of 14 feet after 360 miles.  A wave of equal height but a period of 12 seconds will still be at about 75% of its original height (21 feet) after 360 miles, and will take another 540 miles (total of 900) to decay to 14 feet.

Ah heck, here's the same table, but instead of miles, it's in 24 mile hexes.  I didn't do 6 mile hexes like the last table because most maps don't cover hundreds of miles of ocean 6 miles at a time:

Period	Wave height as a proportion of original height
	90.00%	80.00%	70.00%	60.00%	50.00%	40.00%	30.00%	20.00%	10.00%	1.00%
<10	2	5	8	11	15	20	26	35	50	100
10	3	6	10	15	20	27	35	47	67	133
11	5	10	16	22	30	40	52	70	100	200
12	6	12	19	28	38	50	65	87	125	250
13	8	16	26	37	50	66	87	117	167	333
14	11	24	39	55	75	100	131	175	250	500
15	15	32	52	74	100	133	174	233	333	667
16	23	48	77	111	151	199	261	350	500	1000

I, of course, embarked on a much more detailed, time-intensive course of number crunching before I realized that this short version would probably work more easily.  And thinking about it now, it's probably better to just randomly determine swell on a given day with a 2-3d6 table.  But I think that table will be easier to come up with now that I have a better handle on what it's supposed to represent.

Wind and Waves

It shouldn't take much pondering on my Beaufort Scale post to realize that it's kind of simplistic.  Most people who have been to the beach have seen waves coming in on a windless day, often very big waves.  Almost everyone has seen mud puddles on gusty days and realized that there are no 20 foot waves forming in them.  Straight use of the Beaufort Scale can be a good general guideline for rulings on waves, but leaves a lot up in the air.  Why is that sailors were more comfortable leaving sight of land in the Mediterranean than in the Atlantic in the early days of sailing?  Why are small boats acceptable for working on lakes and inland seas not suited for the open ocean?

When I do research for a game, I start with what I like to call the "picture book" level.  You can get a lot of feel for a place and time by looking at pictures and diagrams of the tools and culture.  Books like Edwin Tunis's Colonial Living and Frontier Living, Richard Humble's Ships, Sailors, and the Sea, and The Diagram Group's Weapons: An International Encyclopedia from 5000 BC to 2000 AD prove that a picture can be worth a thousand words or more.  Many times, depending on the topic, this is as far as research needs to go for the purposes of the game.  I consider the Beaufort Scale to illustrate the weather on this level of research...a simple summary that needs little or nothing done to convert it to game use.

But when the picture book level isn't enough, I move up to the "college intro" level of research.  At this level, I end up reading books and websites aimed mostly at high schoolers and college freshmen or hobbyists.  A lot of game rules fall into this level: the planet-building rules and sublight travel rules for Traveller, the plate-tectonics, meteorology, and oceanography in the 2nd edition AD&D World Builder's Guide, and the engineering in GURPS Vehicles.  When I did the college intro research to add the missing detail from the Beaufort Scale, I was able to answer a lot of questions, but then found I had to do more research.

So what did I find?  It (unsurprisingly) takes a little time for waves to develop.  It also takes some distance over water for the wind to blow (called fetch), which is why lakes and enclosed seas are safer for smaller boats than the wide open ocean. 

The 2002 edition of the American Practical Navigator (downloadable at http://msi.nga.mil/NGAPortal/MSI.portal?_nfpb=true&_pageLabel=msi_portal_page_62&pubCode=0002 for anyone interested) has a somewhat more game-able chart on page 453, which I have made even more game-able by rounding decimals off into whole numbers, and working the fetch lengths out into multiples of 12 miles (in deference to most game maps being at scales of 6 or 24 mile hexes).  I also eliminated redundancy on the table by only keeping breakpoints where either the wave height or the wave period changed.

 Here is a sample of what I have so far.  To use these tables, find the subtable of the Beaufort Number currently in effect, then cross reference the fetch and the amount of time the wind has been blowing.  In the middle of the ocean, fetch is basically unrestricted and you can just look at the time, but lakes and seas can be much more forgiving.  For example, Lake Halli on the Wilderness Map of the Great Waste in X4 Master of the Desert Nomads is about 60 miles across on its long (NW-SE) axis and generally about 36 miles on the N-S axis.  If the wind is blowing at Beaufort #5 from the north, then in 3 hours, Lake Halli will have 4 foot waves; three more hours increases wave height to 5 feet, and in two more hours the waves will be fully developed at 6 feet.  Due to the limited fetch, the waves can't get any higher.  If the wind shifts around until it comes from the northwest, the increased fetch will allow the waves to grow to 7 feet.  Even under winds of Beaufort #8, waves won't exceed 17 feet on Lake Halli.  Wave height (in feet) and period (in seconds per cycle) are limited by the smallest of Beaufort Number, fetch (in miles), and time (in hours).  I have tables for Beaufort Numbers up to 11, and I'll post them eventually. 

Looking up wave development is probably something best left to pre-game prep, along with weather generation, but I think these tables are simple enough to use that they can be used at the game table in case of something changing suddenly, like with a weather control spell.

So we've eliminated momentary gusts of wind from blowing up huge waves, and we've made lakes and seas safer for small boats.  So where do those waves come from on windless days?  This post has gotten pretty long, so I think I'll save the answer to that question for another day.

Inspiration

Haunted

By Don Marquis

A ghost is a freak of a sick man's brain?
Then why do you start and shiver so?
That's the sob and drip of a leaky drain?
But it sounds like another noise we know!
The heavy drops drummed red and slow,
The drops ran down as slow as fate--
Do ye hear them still?--it was long ago!--
But here in the shadows I wait, and wait!

Spirits there be that pass in peace,
Mine passed in a whirl of wrath and dole;
And the hour that your choking breath shall cease
I will get my grip on your naked soul--
Nor pity may stay nor prayer cajole--
I would drag ye whining from Hell's own gate:
To me, to me, ye must pay the toll!
And here in the shadows I wait, I wait!

The dead they are dead, they are out of the way?
And the ghost is the whim of an ailing mind?
Then why did you whiten with fear to-day
When ye heard a voice in the calling wind?
Why did ye falter and look behind?
At the creeping mists when the hour grew late?
Ye would see my face were ye stricken blind!
And here in the shadows I wait, I wait!

Drink and forget, make merry and boast,
But the boast rings false and the jest is thin--
In the hour that I meet you ghost to ghost,
Stripped of the flesh that you skulk within,
Stripped to the coward soul 'ware of its sin,
Ye shall learn, ye shall learn, whether dead men hate!
Ah, a weary time has the waiting been,
But here in the shadows I wait, I wait!

Dragons

Dragons manage to stay on top of the heap in D&D.  Every time someone comes up with a monster that threatens to topple dragons as king of the hill, someone else will create a new dragon that dominates that monster.  I've even seen some discussion about whether it's gone too far...dragons are so powerful according to most game rules these days that there's no way to feasibly include them in a game until the PCs reach phenomenal levels.

I've always recognized dragons as being awe-inspiring creatures, worthy of the greatest of heroes, at least at the high end.  But even as a young kid, I would see paintings of Saint George running down his dragon and be less impressed.  That dragon was the size of a dog.  Not even a really big dog either, but like a border collie.  I'm sure it had a lot of fight in it...it scared the hell out of the locals, for sure...but I don't think Saint George necessarily had to be name level to take it down.

And I wanted to use dragons.  BX dragons as written were still pretty tough for low level parties, and didn't display nearly as much variety as I was able to find in even those less nerd-friendly days, so early in my gaming career, I made a series of tables for randomly generating dragons, from the cute little guys who could hang out on your shoulder to the castle-stomping nightmares that are the standard now.  The original is written on manila paper in pencil and isn't too easy to read anymore, but here it is now, transcribed without any editing.


1) Size
d20        size    base AC                  Hit Dice: (length/5)
1           1-10'       9
2-3      11-20'      7
4-8      21-40'      6
9-14    41-60'      5
15-17  61-80'      3
18-19  81-90'      1
20       91-100'     0

2) Armor
d20        type                       AC adjustment
1-3     leathery                                -0
4-6     hardened leather                   -1
7-10   scales                                   -3
11-19 heavy scales (dragon skin)     -5
20      shell                                       -7

3) Limbs
3a) Legs                      3b) Arms*              3c) Wings                 3d) Fins**                3e) Heads
d20         number         d20      number       d20      number         d20      number          d20      number
1-3              0              1-17        0            1-15        0               1-19         0               1-15        1
4-9              2             18-20       2           16-20       2                20       on each leg    16-19       2
10-12          4                                                                                                               20        2-8
13-18          6
19                8
20              10

*Arms are clawed limbs used for attacking or climbing, but not walking
**Fins include webbed feet and fins on the legs, back, and tail.  If the dragon has no legs, it swims like a water snake.

4) Special Attacks/Defenses
d20         number
1-11            1
12-17          2
18-20          3

Attacks include breath weapons, poison bites, or surprise capability.  Defenses include half damage from certain attacks or better AC on certain parts of the body.

5) Vulnerabilities
d20         number
1-15           0
16-20         1

Vulnerabilities include double damage from certain attacks or worse AC on certain body areas (like the underbelly).

6) Speed
Size         Base Speed
1-10'              18"
11-30'            15"
30-70'            12"
70-90'             9"
90-100'           6"

Modifiers:
   shell: -3"
   wings: double base speed when airborne
   aquatic: 150% base speed in water, 50% base speed on land


Not part of this original dragon generator, but pretty apropos: a dragon classification scheme.


                                        Wings?
Legs                      Y                                N    
0                  Amphiptere                       Wyrm
2                     Wyvern                        Linnorm
4 or more         Dragon                         Drake

Let 'em blow, let 'em blow

One aspect of the weather that gets at least a little attention in gaming is the wind.  The Moldvay D&D Expert rules had a 2d6 table for determining wind speed for sailing purposes.  (This still didn't tie into any other rules, though, like penalties to missile fire for instance.)  Most games I've run into that involved any amount of sailing have had at least a small table breaking out wind speed.  Oddly, as much as I like pirates and nautical things, I don't have 7th Sea, 50 Fathoms, or Pirates of the Spanish Main RPG, so I can't say for sure about them.

But the nice thing about the Moldvay table, and its Rules Compendium descendant, is how easily it maps to the Beaufort Scale.  The Beaufort Scale was developed in the early 1800s as a way to estimate wind speed from its effect on the environment, particularly in the formation of waves on the ocean.  It ranges from 0 (calm wind, still water) to 12 (hurricane winds, waves 45 feet or higher).  By working backwards, knowing the wind speed, a game master can use the Beaufort Scale to describe sea conditions.  Using 2d6-2, a game master can dispense with the official table and just go straight to the Beaufort Scale, generating a result from Calm to Storm, leaving the Violent Storm and Hurricane levels of results as major events (as discussed in the Rules Cyclopedia, chapter 12, Strongholds and Dominions). 

Rerolling wind speed every day on a 2d6 scale makes it pretty swingy.  During one of Sir Francis Drake's voyages, his fleet was hit by gales for 52 days, making a very unlikely string of dice rolling, even if we consider all results of (9-2=) 7 and up as fitting the bill (Beaufort scale results of 7 are Moderate Gales, 8 are Fresh Gales, 9 are Strong Gales, and 10 are Storms).  I'd recommend rolling once a week, and varying the daily wind speed by no more than one step up or down from there.  Drake's string of stormy weather would still be pretty unlikely--at least seven straight 25% rolls--but a lot less unlikely than 52 of them.

Certain areas could have different dice rolls for wind speed.  Trade winds tend to be pretty steady, and not too stormy, so maybe 2d3+1.  A Sargasso Sea-type area, where ships are trapped by thick seaweed and light winds, could be d6-4.  A continuous storm on a fantasy world, like the Eye of Abendego on Pathfinder RPG's Golarion would be something like d4+8.

One final note about the Beaufort Scale: wave height can be pretty important in a game.  A ship is likely to capsize if it is hit by a wave more than twice its length if hit head-on or directly from behind (astern).  If it's hit from the side (abeam) it will capsize if the wave is more than twice its width.  Outriggers and catamaran style ships count the full width for this purpose...the Polynesians sailed the Pacific in these types of ships for a reason.

Talking about the weather

It seems to me that most any game should take the weather into account, particularly pre-modern games.  Maybe a city-based noir game doesn't need much weather aside from some rain for atmosphere, but the inhabitants of a medieval fantasy world will be hugely affected by rain, snow, high heat, and high winds, especially if they need to travel any distance cross-country.  I've known more story-oriented gamemasters to argue that the weather should be chosen based on story needs, but more often than not, that means the weather is always somewhat cool to somewhat warm, partly cloudy, with moderate breezes and no precipitation.  Even sandbox gamers, usually happy to roll dice and consult tables, tend to ignore the weather.  At best, weather effects are written into the adventure, like the notes about high temperatures and heat damage in the Sind Desert and Plain of Fire in Master of the Desert Nomads (X4). I have to admit that I often overlook it myself, although I have fiddled with various weather rules over the years.

I've seen a lot of tables describing the temperature highs and lows and daily chance of rain for each month for a given area.  The campaign sourcebooks for Iron Crown Enterprises' MERP/Rolemaster were pretty good about this.  The problem with these is they're pretty well tied to that area, and while you could repurpose them for areas of similar climate in your homebrew game world, not every area is well represented.  Middle Earth is heavy on temperate areas and high mountains, but pretty light on jungles and tundras.

The AD&D Wilderness Survival Guide has a decently workable system, maybe a little too detailed and a little too fiddly to use at the table, but pretty good if you prepare ahead of time and your players don't suddenly decide to go mountain climbing in the middle of your forest exploration session.  It's a generic system, covering pretty much every realistic terrain type found on Earth. Lately I've been pretty happy with Spes Magna Games' Dodeca Weather.  It's a little more streamlined and easier to work with at the table, although it still helps to prep ahead.

For non-realistic weather, the thing that pops into mind for me is The Epic of Aerth for Mythus.  If you're not familiar with this book (great sourcebook if you don't want to build a world from scratch, and great inspiration if you do), it covers an earthlike surface world, a primitive hollow world filled with dinosaurs and ice age critters, the long winding caverns filled with a weird underground ecology (Gygaxian naturalism in its most developed state), and the parallel world of Faeree.  Faeree is where the weather angle comes in, with several pages of tables devoted to the strange changes that occur regularly to the environment, including the sun, moon, stars, clouds, plants, and animals of the world, as well as the rate at which time passes relative to the "real" world for characters exploring the Faeree lands.

Way back in the day, I had cobbled together a fairly simplistic weather chart using the weather effects listed in the Moldvay D&D Expert set under the Control Weather spell and the terrain/biome types I found in the Funk and Wagnall's encyclopedia we had at the time.  It was just a broad overview, and didn't provide enough detail on rainfall or snowfall to adjudicate travel effects or flooding, but it was super simple...front and back of a page of notebook paper.  I wish I still had it.  I think I tossed it when I got the WSG, or maybe sometime later in all my military moves.

At any rate, I'm always interested in seeing new systems, and how other DM/GMs handle things like this.  Show me how you make it rain.

First!

So, I officially retired from the Army a year ago today.  As a life-long gamer, I was looking forward to that day for a long time.  The Army tends to suck up a lot of your time, and when you do have time, you're often too tired to use it for anything but sleeping or laying around.  And a lot of the people you work with don't want to do anything more complex than get drunk when you do have time and aren't too tired.  I had a pretty good gaming circle when I lived in Maryland, but military life is unsettled, and it wasn't long before I was moved again.

I played a little D&D with my kids, starting when they were fairly young.  Basic Moldvay D&D, moving up to the Rules Cyclopedia (not a huge stretch) once they reached third level.  I expected once I retired that we'd have a regular game going on, and would make a pretty good run for that full 36 level experience, but alas, they are teenagers now, and spend time with people their own age, or playing computer games mostly.  I can get them to play boardgames here and there, but I got tired of feeling like I was forcing them into role-playing. 

And so, I need a creative outlet.  I'm a late-comer to the blogging world...I only discovered game blogs about two years ago.  I've spent a lot of time (a LOT of time) looking over game blogs, mostly related to Old School D&D.  A lot of good stuff out there, but unfortunately, a lot of blogs lay abandoned, gathering dust like the tombs they used to describe.  And so, I consider it my duty to become a point of light in this post-apocalyptic wilderness of game blogs.  Hopefully I can give some inspiration back to the community in return for all the cool shit I've been given.